Various types of electronic systems include digital amplifiers adapted to process and amplify digital audio signals. For example, portable media player devices, cellular telephones, radios, audio recorders, stereo equipment, and other systems may include digital amplifiers, which process and amplify voice, music, and other types of digital audio signals. During amplification, a digital amplifier may introduce non-linearity and noise into an output signal. The non-linearity and noise, referred to generally as “distortion,” may be quantified in terms of signal-to-noise ratios (SNR), signal-including-noise-and-distortion (SINAD) ratios, or other quality measurements. Significant distortion, left uncompensated for, may result in poor signal quality and low end-user satisfaction.
Recently, manufacturers of portable media player devices have discovered that attention to playback time, a relatively new consumer-driven constraint, also is important to produce products that will be successful in this highly-competitive and lucrative market. “Playback time” refers to the amount of time that a portable media player may output an audio and/or video signal given a full battery charge. A device's playback time may be affected by various manufacturer-influenced factors, including battery capacity and digital amplifier power consumption and efficiency, among other things. With respect to battery capacity, technologies continue to be developed that result in batteries having higher power densities (i.e., the ratio of power available from a battery to its volume). However, the drive toward producing smaller and smaller devices also continues, thus constraining battery volumes and, accordingly, battery capacities. As manufacturers of electronic systems continue to face market pressures relating to high audio quality, smaller device sizes, and longer playback times, a need exists for digital amplifiers, electronic systems, and amplification methods, which are adapted to produce high-quality output audio signals in an energy-efficient manner.